Nissan Motor Company Limited

Yoshinori Iwasaki

Nobusuke Toukura

Yasushi Narita

Masayuki Yasuoka

Tatsuya Nagato

Tomoya Kimura

Yoshinori Tanaka

Hiroshi Abe

Hideaki Watanabe

Shojiro Sato

Katsuhiko Tsuchiya

Shusaka Katakura

A controller calculates a target speed ratio of a continuously variable transmission incorporated into an infinitely variable transmission for a vehicle and a target vehicle speed according to a vehicle running state. When a predetermined creep torque limiting condition holds, the controller limits the target vehicle speed such that the difference between the target vehicle speed and the real vehicle speed is within a predetermined range. By controlling the speed ratio of the continuously variable transmission such that this difference diminishes, the infinitely variable transmission generates a creep torque consistent with the intention of the driver.

Control of infinitely variable transmission

A controller ( ) calculates a target speed ratio of a continuously variable transmission ( ) incorporated into an infinitely variable transmission for a vehicle and a target vehicle acceleration based on a vehicle running state. When a predetermined creep torque control condition holds (S -S S ), the controller ( ) corrects the target speed ratio such that the deviation of the target acceleration from the real vehicle acceleration to decrease. By controlling the speed ratio of the continuously variable transmission to the corrected target speed ratio, the infinitely variable transmission generates a creep torque consistent with the driver's intention.

A control system for an engine-CVT powertrain controls the target driving force during traveling on a ramp to meet operator power demand and/or the target input speed of the CVT to accomplish the ramp target window during traveling on the ramp to meet operator deceleration command.

Engine transmission control system

An ordinary target driving force is generated against a detected value of the vehicle operator depression of an accelerator pedal and a detected value of the vehicle speed. The ordinary target driving force is a driving force required to keep the vehicle rolling on a flat horizontal road at the detected value of vehicle speed with the detected value of the vehicle operator depression of the accelerator pedal. A running resistance increment, i.e., an increase of running resistance from a standard running resistance, is calculated. A preliminary driving force correction is determined in response to the running resistance increment. The preliminary driving force correction is subjected to variation. The preceding old value of a driving force correction is subtracted from a current value of the preliminary driving force to give a variation in driving force correction. This variation is limited to fall in a range between an upper and a lower limit to give a limited driving force correction variation. The preceding old value of the driving force correction is added to the limited driving force correction variation to give the driving force correction. This driving force correction is added to the ordinary target driving force to give a corrected target driving force. To realize the corrected target driving force, engine torque and CVT ratio are adjusted.

Vehicle driving force control with differential dependent correction

In a vehicle equipped with a continuously variable transmission, sensors detect a vehicle speed, an accelerator depression degree and an output rotation speed of the transmission. The minimum required drive shaft drive torque is calculated from the vehicle speed and the accelerator depression degree. A target input rotation speed of the transmission for achieving the minimum required drive shaft drive torque with the least engine fuel consumption is calculated according to the vehicle speed. The input rotation speed is controlled to this target input rotation speed. The target engine output torque to generate the minimum required drive shaft drive torque is calculated, and an engine throttle opening is controlled to obtain this torque. As a result, the required vehicle drive force is obtained with the minimum engine fuel consumption.

Vehicle drive force controller

A regional attribute for a region in which a vehicle is traveling is detected by a vehicle navigation device, and vehicle drive force characteristics such as a throttle gain of an electronic throttle or a speed change pattern of an automatic transmission are modified according to the regional attribute. An operation amount of an accelerator operated by a driver is detected, and by not modifying the drive force characteristics when the accelerator operation amount is not zero, abrupt change of drive force is avoided, and the sense of discomfort experienced by a driver due to abrupt change of drive force is eliminated.

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Yokosuka, Japan

Yoshinori Iwasaki